Use PIC relocation mode by default for PowerPC64 ELF

Most of the PowerPC64 code generation already creates PIC access. This
changes to a full PIC default, similar to what GCC is doing.

Overall, a monolithic clang binary shrinks by 600KB (about 1%). This can
be a slight regression for TLS access and will use the TOC more
aggressively instead of synthesizing immediates. It is expected to be
performance neutral.

Differential Revision: https://reviews.llvm.org/D26564

llvm-svn: 289744

1 files changed, 9 insertions, 1 deletions

diff --git a/clang/lib/Driver/ToolChains.cpp b/clang/lib/Driver/ToolChains.cpp
index 46707aa06ba..968b0cb4724 100644
--- a/clang/lib/Driver/ToolChains.cpp
+++ b/clang/lib/Driver/ToolChains.cpp
@@ -2879,7 +2879,15 @@ bool Generic_GCC::IsUnwindTablesDefault() const {
 }
 
 bool Generic_GCC::isPICDefault() const {
-  return getArch() == llvm::Triple::x86_64 && getTriple().isOSWindows();
+  switch (getArch()) {
+  case llvm::Triple::x86_64:
+    return getTriple().isOSWindows();
+  case llvm::Triple::ppc64:
+  case llvm::Triple::ppc64le:
+    return !getTriple().isOSBinFormatMachO() && !getTriple().isMacOSX();
+  default:
+    return false;
+  }
 }
 
 bool Generic_GCC::isPIEDefault() const { return false; }